I have never seen that movie where they do it like Saw or whatever? But i am sure anyone would in the situation given.
Saw is a lot different than this. He merely says "sacrifice," so I think it's painless too, and you don't have to do it yourself. I vote my left leg, cause prosthetics are getting pretty nice these days.
Japanese Yakuza gangsters have a custom of cutting off a finger on your own hand after seriously offending someone as an apology, sort of a symbolic suicide without killing yourself like they did in the past heres a funny clip from a manga like movie, where one bad mf takes the ritual suicide to the whole new level by cutting off his tongue, http://www.youtube.com/watch?v=7xG74Vr5_fQ